Homework Help: math

Posted by Jon on Saturday, February 9, 2008 at 1:39pm.

Age 0-14 number of people= 206,423
Age 15-34 number of people= 265,778
Age 35-54 number of people= 308,946
Age 55-74 number of people= 159,092
Age over 74 number of people= 69,264

1)Classify the data in the table.
A)positively skewed
B)negatively skewed
C)normally distributed
D)discrete distribution
My first choice was C but I went with A instead.

2)For 2000 patients, a blood-clotting time was normally distributed with a mean of 8 seconds. What percent had blood-clotting times between 5 and 11 seconds?
A)68%
B)34%
C)49/5%
D)47/5%
I chose A

3)During a sale, 1/6 of the CD prices are reduced. Find the probability that 2 of 4 randomly-selected CDs have reduced prices?
A)5/36
B)25/1296
C)25/216
D)5/216
I dont know

4)A music teacher wants to determine the music performances of students. A survey of which group would produce a random sample?
A)students in the school band
B)students attendeing the annual jazz concert
C)students in every odd-numbered homeroom
D)every other player on the baseball roster
I chose B

5)In an election poll, 56% of 400 voters chose a certain canidate. Find the margin of sampling error.
A)5%
B)2%
C)4%
D)7%
I chose A

math - PsyDAG, Saturday, February 9, 2008 at 2:22pm
1) sounds fine.

2) How can you determine the percentages without knowing the Standard Deviation? You need a measure of variability.

3) The probability of picking a reduced DC is 1/6, not reduced = 5/6. The probability of picking 2 of each is 1/6 * 1/6 * 5/6 * 5/6 (multiply).

4) A random sample means that every student has an equal probability of being in the sample. Reconsider your answer.

5) Right.

I hope this helps. Thanks for asking.
math(correction) - Jon, Saturday, February 9, 2008 at 3:01pm
I'm sorry #2 says For 2000 patients, a blood-clotting time was normally distributed with a mean of 8 seconds and a standard deviation of 3 seconds. What percent had blood-clotting times between 5 and 11 seconds?

Is #4 A?

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